In prior applications of one of the present inventors, there are disclosed various methods and apparatus for illuminating, primarily, though not necessarily, with infrared, various body parts in the region of a body invasive procedure which body parts are to be protected against inadvertent cutting or other damage or trauma. Infrared light energy is preferred since such energy penetrates surrounding tissue to a significantly greater extent than visible light. In this regard see application Ser. No. 08/355,164 filed Dec. 8, 1994, pages 27 and 28.
In one such exemplary method of the use of the infrared light energy in surgery, a catheter is inserted into the ureter of a patient and a light guide is inserted into the catheter. The light guide is modified such that a predetermined length of the distal end of the guide will, when the proximate end is connected to an infrared light source, emit infrared light energy generally transverse to the length of the guide. Various means may be used to detect the infrared light energy and thus locate the body member to be protected.
The various means for detecting the infrared light energy may include a video camera sensitive to such energy, means for display of an image thus produced on a monitor along with images of the site of the operation, a detector that provides an audible or visual indication of the location of the body member to be protected or a combination of both approaches.
In the systems as presented in the prior applications the visual and infrared images are processed through the same signal channels, it was not possible with the equipment disclosed therein to independently manipulate the signals to selectively enhance one set of signals relative to the other or to apply various digital techniques to both signals to enhance viewing of the site of the procedure. Further since infrared and visual light do not normally focus at the same distance from an imaging lens one of the images may be slightly blurred relative the other.
An additional problem that has developed is in the use of an endoscopic light source. The source introduces infrared light into the region of the surgery or of investigation. Such additional infrared light reduces the gain of the system to infrared light. Further the removal of the IR filter from the laparoscopic camera reduces certain color compensation provided by such filter and, for instance, causes dried blood to look almost black instead of dark red.